Duvidha
Based on a Rajasthani folk-tale, Duvidha is the story of a merchant’s son who returns home with his new bride, but is sent back to look after his family business. A ghost falls in love with the bride and takes the form of her absent husband and lives with her. She gives birth to his child.
Starring Ravi Menon, Raisa Padamsee, Hardan, Manohar Lalas, Bhola Ram, Kana Ram, Shambhudan
Watch "Duvidha" on Mubi released in 1973. It's a drama and fantasy movie, and has a rating of 7 out of 10 from Imdb which is usually fine for this kind of movie.